An increasing occurrence of ectopic pregnancy has been reported in many parts of the world, including a threefold increase in the United States during the last decade. The little that is known of the etiology of ectopic pregnancy can account for only a small fraction of the currently high rate. We plan to identify and interview the approximately 425 female members of the Group Health Cooperative of Puget Sound (GHC) who develop an ectopic pregnancy between October 1, 1981 and September 30, 1986. To estimate the exposures of women in this population to various potential etiologic factors, a sample of approximately 850 demographically-comparable women from the GHC membership file will be identified and interviewed as well. The interview will focus on exposures whose increase in prevalence parallels the change in ectopic pregnancy incidence, namely: feminine hygiene practices (expecially douching), use of certain contraceptive methods, induced abortion, venereal disease, and pelvic inflammatory disease.